Glow discharge polymerization has been shown to be an effective method of modifying surface properties without affecting bulk properties of materials. Such coatings can be used to enhance the blood and tissue compatibility and adhesion of polymeric prostheses. Highly crosslinked surface films formed by glow discharge treatment have been demonstrated to inhibit plasticizer leaching from PVC tubing. A systematic study of methods of reducing crosslink density in glow discharge polymers, with a view to producing coatings resistant to micro-crack formation on flexing, is proposed. The enhanced barrier properties of glow discharge polymers of low crosslink density will be demonstrated. The study will be carried out using a reactor capable of coating tubing and designed so that the results can be extrapolated to reactors of different dimensions or geometry, e.g., for coating the inside of small vessel prostheses. Additional benefits, such as a greater variety fo functional groups accessible by glow discharge polymerization and reduced free radical concentration in the coatings, are also expected to accrue from the proposed research.